Figure 3.

Reduced [Ca²⁺]_i response of microvascular endothelium to H₂O₂ with advanced age

A, exposing endothelium from Young mice to 200 μm H₂O₂ for 20 min progressively increased [Ca²⁺]_i (ΔF₃₄₀/F₃₈₀). [Ca²⁺]_i recovered during 30 min washout of H₂O₂ with PSS containing 2 mm Ca²⁺. Removing extracellular Ca²⁺ (0 [Ca²⁺]_o) during H₂O₂ exposure prevented the rise in [Ca²⁺]_i in endothelial tubes of Young mice yet [Ca²⁺]_i increased within 5 min of H₂O₂ washout with PSS containing 2 mm Ca²⁺. B, as in A for Old mice; note diminished [Ca²⁺]_i response compared to Young in the presence of 2 mm [Ca²⁺]_o and negligible [Ca²⁺]_i response in 0 [Ca²⁺]_o. Summary data are means ± SEM. For both age groups n = 9 for 2 mm [Ca²⁺]_o during H₂O₂, and n = 7 for 0 [Ca²⁺]_o during H₂O₂. *P < 0.05, versus Control. ^#P < 0.05, Old versus Young for given time and condition, ^ΨP < 0.05 for 0 [Ca²⁺]_o versus 2 mm [Ca²⁺]_o exposed to 200 μm H₂O₂.